At 6800 rpm, a 383 pulls 753 cfm of air at 100 percent efficiency. Running two 750 Dps, they will work well about there, but probably not very good below there. I would call Holley tech and ask what they recommend. There are other options, like vacuum secondary carbs that might be better suited to your deal, especially if you don't have a 5,000 or higher stall converter.